


The Strange Sounds

by QuickySand



Category: Undertale (Video Game)
Genre: Alternate Universe - Underswap, M/M
Language: English
Status: Completed
Published: 2016-01-11
Updated: 2016-02-07
Packaged: 2018-05-13 04:13:50
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 5,373
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5694313
Author URL: https://archiveofourown.org/users/QuickySand/pseuds/QuickySand
Summary: <blockquote class="userstuff">
              <p>Sans wakes up one night to something unusual, but finds something a little... 'Strange', when he tries to ask Papyrus about it.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> This is my first Underswap! :D I'm actually really proud of it!!
> 
> (Please, take this as my apology for SBL taking so long!)

   Sans woke up to strange sounds from the room next to his. _Strange,_ He thought, _Usually I hear those noises early in the morning. And whenever I ask Papyrus about it, he gets all orange in the face and says not to worry about it…_ The small skeleton sat up in his teal-coloured racecar bed, loose t-shirt hanging off one shoulder. _Why are they so early, tonight? Is my brother okay?_ He stood up, the tail of his shirt flowing around his bare pelvis and the tops of his femurs. _I should go check on him._ Sans quietly opened the door to his room and stepped out, footsteps naturally silent as he made his way down the short hall. The strange sounds grew louder as he neared the door to his brother’s room. Silently, as Alphys had taught him, Sans pushed open the door and let his eyes adjust to the lack of light. They quickly widened; Papyrus was sitting up in his bed, back pressed against the wall, usual hoodie halfway up his ribs. His cheekbones were dark orange, his eyes half-mast, as one hand let phalanges roughly stroke his ribs and the other hand pumped a glowing orange shaft at his pelvis. “Ah… Ah… Oh… Ooh…” Sans furrowed a non-existent brow; those sounds were coming from his brother? Why?

“Brother?” Papyrus shot up, eyes wide and face bright orange as he stared fearfully at the doorway.

“S-Sans!!” He exclaimed, pulling his blankets over his lap. “H- _Heyyy_ , bro!” Sans, still curious, shuffled inside and shut the door respectfully behind him. He then took a seat next to his brother on the bed, causing Papyrus to tense up and gulp nervously.

“What are you… doing?” The taller skeleton relaxed a little with a stunned expression, staring into his sibling’s wide, curious eyes.

“What… What do you mean?”

“With your hands. What were you doing to yourself?” Papyrus was amazed and afraid; his brother was a grown monster and should know about this sort of thing, but if he didn’t, could he really taint him?

“I-I was masturbating.” Sans cocked his head to the side; he might have heard that word from Alphys, before.

“Master-what? What’s that?” Papyrus’ heart nearly stopped as he began to sweat anxiously.

“Oh, well, uh… It’s, uh… W-Where you, um… Aha… Y-You-”

“Why don’t you show me?” Papyrus’ eyes widened even more as he squeaked in surprise.

“W-What?” He stammered, relaxing again when Sans gave him a broad, innocent smile.

“You’re having trouble with your words, so why not just _show_ me, instead?” The taller skeleton was instantly ready to pull his sheets back off.

“A-Are you sure?” An eager nod.

“I’m _always_ ready to learn, Pap!” Papyrus let out a shaky breath and uncovered himself, not as aroused as he was before due to the scare he had been given a few moments ago. A quiet moan escaped past his teeth as his fingers wrapped around the base of his cock and gave a slow stroke up and down. With quick, delicate strokes and the knowledge that his brother was watching him in the back of his mind, Papyrus was back to full length in no time.

“A-Ah… Mm, oh…” He had begun to moan again, eyes half-mast and cheeks a darker shade once more.

“You’re making such weird noises, Papyrus. Are you okay? Does it hurt?” The taller skeleton bucked his hips up a bit as his brother spoke.

“No, it feels… O-Oh… Mm, so good…” His breath came out in shaky puffs as his body trembled with desire, knowing that Sans was barely a few inches away. “Ah… A-Ah… S- _Sans_ …” He hadn’t meant for that to slip out of his mouth. The smaller skeleton let his gaze flick up to his brother’s face, which was contorted in pleasure, his own face feeling a bit warm.

“Yes, brother? Do you need assistance? Would you like my help?” Papyrus bucked his hips again at the thought, muttering a barely-coherent “Please”. “A-Alright! I guess I’ll just… Mwehehe!” A smaller hand joined the longer hand in its up and down motions, forefinger and thumb unintentionally teasing over the head. Papyrus’ body began to tremble, his moans growing in volume. “So _this_ is a dick, huh?” Papyrus groaned at hearing his brother say such a word, nodding as best as he could as he clenched the bedsheets tightly in his fingers. “Am I doing alright, brother? I’m not hurting you, am I?” The taller skeleton let his own hand fall away to give Sans more room to work.

“Yes, _yes_ … Nh, S- _Sans_ …”

“Y-Yes, Papyrus?” His voice betrayed his worry about whether or not he was performing well.

“Doing… S-So _good_ … Ha- ah…”

“Really?!” It was an excited chirp that brought a strained chuckle from Papyrus’ throat.

“Y-Yeah, but… Ah… Could you…? H-Harder…”

“You want me to… Grip you tighter?” A gentle squeeze earned a grateful gasp.

“ _Please_!”

“Alright, alright, mwehehe. I saw you doing _this_ , too…” A loud gasp when fingers wrapped around a rib and tugged carefully.

“A-Ah! Fff… Sshhhi.. Oh, stars… Sans, c-could you… Touch my spine?”

“Of course, brother! How would you like me to do it?” Papyrus tried to work through the haze of his mind to give his brother clear instructions… His _brother_.

“Wait, no, Sans, _stop_ ,” He choked out, though it pained him to do so, “We shouldn’t do this.” He was both relieved and disappointed when the motions stopped. Sans was pouting when he looked up.

“W-What do you mean, Paps?”

“We’re brothers… O-Only lovers are supposed to do this. This-This isn’t right.”

“What? What does being brothers have to do with anything? We love each other; we’ve said it plenty of times before!” _Yes, but not like…_ “And why would making you feel good be a bad thing? You’re obviously really enjoying yourself, and I’m enjoying myself by making you happy, so why would that be wrong?” Breathing heavy, soul warmed and genuinely touched, the taller skeleton smiled.

“Well, I can’t argue with _that_ logic...” Sans brightened again.

“Exactly! So tell me what to do, brother!” A shy orange blush.

“M-My spine, uh… Maybe just… Fffeel along the grooves of it?” Sans nodded happily, careful fingers tracing each dip and line, thumb rubbing as the hand steadily made its way up. Satisfied moans and sighs spilled from Papyrus’ mouth, turning into a startled choke when his spine was firmly grasped near his ribs.

“Oh, uh, too much?” The taller brother quickly shook his head.

“P- _Per_ fect,” He wheezed, vision blurring from this new source of pleasure, “Ju-Just right, Sans, now can you…? Oh, yes, just like that…” Sans chuckled at the sight of his brother, normally tense or distant or both, turning to putty in his hands as he stroked both his spine and member in turn. “Yes, oh… Y-You’re going to want to… Nh… Rub t-the tip a bit. O-Oh…!! Hh…” Vision rolled up before eyes shut, Papyrus breathing heavily through gritted teeth.

“Are you alright, Papyrus?” A quick, eager nod.

“Yeah, bro, I’m just… O-Oh, s-so close…!” It turned into a near-desperate whine near the end, confusing Sans.

“Close? Close to what?” Papyrus was too out of it to chuckle, but managed an answer through his moans and soft pleas.

“C-Climax, oh stars! Oh stars, don’t stop…!! S-So… Close, almost… Almost…! Almost! A- _Ha_!” Sans yelped and pulled back when Papyrus let out a cry and arched his body outward, orange spurting from his member and coating his ribs. “Ah! Ah…! Ah… Ha…” He relaxed back down against the wall, panting softly as he tried to regain himself.

“W-Wowzers! What was that, Paps?” Sans asked nervously, looking his brother up and down. He was too engrossed in worrying for his brother to notice how his body was reacting to what his brother had just done.

“That was… Ha… C-Cum. Semen. I jizzed, bro, and it felt so good…” Sans’ eyes widened a bit; so _that’s_ what semen was. “Thank you, Sans.” The smaller skeleton brightened once more.

“It’s no problem at all, Papyrus! I’m glad that I could help! But I have a question…” Papyrus, still a bit dazed from what he currently deemed his best orgasm ever, hummed in response. “Am I able to do that, too?” The taller skeleton blinked in surprise after finally regaining himself.

“I mean, yeah, probably. If I can, you can, ya know?” Sans nodded and closed his eyes, and it was finally noticed that his breathing was shaky and his face was bright blue. It took little-to-no effort to summon his member, and he stared at it in surprise.

“It… Looks different from yours.” No response. “Paps?” He looked up, worried that something was wrong, only to see that his brother was staring down at him with wide eyes and a thick orange blush. “B-Brother? Is-Is something wrong with it?” Papyrus quickly shook his head, moving closer.

“No, not at all, Sans. It’s beautiful! A beautiful little cock… May I touch it? I feel like I should return the favour.” Sans smiled a bit.

“You don’t have to, Papyrus, it’s al- Uh?” He let out a confused grunt as he was laid onto his back, Papyrus leaning over him.

“Let me help. I _want_ to help.” Sans smiled nervously at the strange, rather lewd expression on Papyrus’ face.

“A-Alright, brother! W-What are you going to d-do?” Papyrus hesitated, taking on a shy demeanor.

“Can we…? Could we… kiss?” Sans furrowed a brow with a more confident smile.

“Without going on a date, first? I don’t know, brother, the dating manual says-” Papyrus growled softly and this instantly shut Sans up with a shiver.

“Forget the stupid manual! I’m asking if I can kiss you.” Sans nodded quickly, not quite knowing why, and his sibling swooped in. The kiss, on Papyrus’ end, was hungry, while on Sans’ end it was shy. A gentle orange tongue flicked at strong white teeth and the smaller skeleton instinctively opened his mouth with a quiet sigh. “Nn…” A slim hand slipped behind a round skull and tilted it back a bit for better access.

“Mmn, b-broth- Mm…” Papyrus swallowed up his brother’s sounds with another kiss, tongue playful, hands gently spreading short arms away from a broad chest. One arm was folded downwards on the sheets at Sans’ side, the other folded upwards by his head. A soft, shaky moan as hands slid up the nightshirt to drag fingers lightly across sensitive, untouched ribs. Papyrus broke the kiss and let his mouth wander down to his brother’s neck, chewing the cervical lightly. It was suddenly very clear to Sans why his sibling had made those weird noises, hundreds of them leaking past his own teeth and causing Papyrus’ body to quiver with desire.

“You’re so hot, Sans… So adorably sexy…” Papyrus breathed, puffing hot air onto his brother’s neck. A whimper of a moan was his response, sending shivers down his spine.

“P-Pap… Nn… P-Please…” Papyrus looked up, eyes half-mast and eager to hear what his brother had to say.

“Yeah, bro?” A light stroke to his ribs and Sans arched slightly.

“Nn, _yes_ … Please, t-touch me more…! Touch my c-cock!” The taller skeleton choked on his own breath, eyes wide as Sans stared pleadingly down at him. How could he say no to that? A strangled whimper when fingers brushed the stiff shaft made Papyrus hesitate, then smirk. “W-What are you…? B-Brother?”

“I’m going to make you feel _fantastic_ , Sans, just wait…” The taller brother whispered sensually as he moved down his sibling’s body, leaving kisses and nips in his wake.

“H-How- Ah! Ahn…! Mm…” Sans bit into the knuckle of a pinkie, closing his eyes and letting his head fall back onto the pillow as a firm lick was applied to the base of his member. Papyrus chuckled, pressing little kisses and sucks along the sides before laying his tongue flat on the tip and giving another firm lick, lapping up pre. “Oh, stars, please, brother… O-Oohh…” A long, throaty moan as Papyrus let his brother’s cock into his mouth, allowing it to sink into the heat. Fingers scratched at the back of his skull as Sans whimpered, eyes tightly shut and other hand clutching messy bedsheets. Little whimpers and moans fell out of a trembling mouth as Papyrus bobbed his head up and down skillfully, moaning with each suck. “Ah… Ah, nph… Hn… Ha? O-Oh, my… P-Papyrus?”

“Hm?” The soft hum of a response drew out another moan.

“Y-Your… Your dick is back.” The taller skeleton shivered.

“Mm.”

“N-Nph… A-And I don’t know why… But I… I-I want it in me.” Papyrus choked and shot up with wide, disbelieving eyes, wiping the drool off of his mouth and onto his sleeve. Sans squeaked, eyes wide as well, but with fear.

“You want me to fuck you?!” The smaller brother’s expression quickly turned to outrage.

“Language, brother!” Then he looked away, shy again. “B-But yes. Is that… Is that bad…?” The taller of them laughed, shrugging off his shorts completely.

“Are you kidding me, bro?! Do you know hard hearing you say that makes me? It sounds so damn good…” Sans gave a start, eyes wide in surprise.

“O-Oh? Well… I want you to bone me.” Papyrus shivered with a grin, sitting back on his legs and pulling Sans’ pelvis up near his. “Brother, I want you in me.” The smaller skeleton wiggled his hips eagerly, biting his tongue. “ _Papyrus, I need you to fuck me_ -” And then the tip was in. Papyrus let out a cracked moan and Sans cried out brokenly. “P- _Papyrus_! Hn…!! D-Deeper, please!!” Papyrus groaned and sank in further at a slow rate, not wanting to hurt his precious brother. “Ahh, more…” He didn’t stop until he was all the way in, Sans a bundle of quivering, blushing bones against him. “Nn… N-Nn… Ah…”

“Are… Are you okay, Sans?” A shaky nod and broad, trembling smile.

“S-So good, Paps… P-Please, move, brother…” A slowly, small thrust was followed by a loud moan. “Oh, ff _fuck_ , please, more!” And that’s what started their quick, desperate pace. “Hn! Hn! Nn! Hn! Ah! Oh! Pappy! Ah! Yes!”

“Oh…! Oh…! Ooh…! Ha…! Sansy… ! Ooh…! Oh…!” They were both already so close, clutching desperately at each other’s bodies wherever they could reach.

“Ha- Mm! M-Mm…!” A hungry kiss muffled their sounds as their movements grew faster and faster, tongues dancing sloppily in the space between their mouths before dipping past each other’s teeth curiously and eagerly. When Sans finally came for his first time, he broke the kiss to throw his head back and arch his body with a scream. “ _Papyrus_!!” Barely another thrust and Papyrus had reached his climax as well.

“ _Sans_!! Nh!”

“Ah!”

“Ah, ha, ha…”

“Ha… Mm…” Papyrus carefully lowered himself down beside his brother, head on the pillow and cheek against his sibling’s as the cuddled close. “Mm… That was… Wowzers, brother, that was unlike anything I’ve ever experienced before…!”

“Heh… Was it good?” A nod as Sans nuzzled his face against Papyrus’ cervical, giving it a gentle lick as he was cradled.

“I love you, Papyrus. I _love_ you.” A quiet, shaky gasp, then a wheezy chuckle.

“I love you too, Sans… Good night.” They both figured that, in the morning, they could make some more beautifully strange sounds.


	2. The Thrilling Sequel

**Summary for the Chapter:**

> Just fucking read, it took me forever to type this up while sinning with the fam ;v;

   Sans woke up late, to his displeasure. To his _pleasure_ , he woke up in his brother’s bed, held in his brother’s arms. And to his discomfort, there was a dull, throbbing pain in his spine and pelvis. He shifted uncomfortably, trying to get rid of the ache, and smiled when his brother pulled him closer. “Good morning, Papyrus!” He chirped, though his voice was raspy and his throat felt raw.

“Mm… Mornin’, bro.” Papyrus mumbled sleepily and Sans giggled, then winced.

“My spine hurts…” His huff turned into a pleased sigh at the end as his brother began to massage his sore bones.

“Sorry, that might’ve been my fault.”

“Hm?”

“I might’ve fucked you a bit too hard, last night.” Sans’ eyes widened and his face flushed a bright blue as memories of the night before flooded his mind. He relaxed with a warm smile and nuzzled Papyrus’ neck with a content sigh, giving it little kisses of gratitude. The taller skeleton shivered, his grip tightening on his brother’s pelvis, which he had been massaging carefully, and earning a moan of approval. A tongue was added in the attention to his cervical, causing him to bit his tongue.

“Last night was fun,” Sans murmured, licking up under his brother’s chin, “Felt real good, Pappy. Glad we did it. Wouldn’t mind doing it again…” Papyrus shivered, fingers lightly scratching his brother’s ilium and drawing out another moan.

Heh, w-when and where, bro-?” He was surprised when he was rolled onto his back and straddled by Sans, and even more surprised by the lust and need in Sans’ eyes as he stared up at the smaller skeleton.

“Here… Now.” Papyrus gulped, his eyes wide and a familiar sensation _down there_. Sans seemed too have the same problem, if the glowing blue bulge under his large nightshirt had anything to say. Pap was at a loss for words. “Hm, I wonder what it would feel like if I…” Sans shifted his lower body down, hands holding Papyrus’ wrists just above his skull with surprising strength. Sans brushed their members together with a shaky exhale, and Papyrus’ breath hitched. They were both already panting softly, bodies trembling slight in anticipation. The smaller skeleton ground roughly down against his brother, letting out a whimper and closing his eyes as his brows furrowed. Papyrus groaned and jerked his hips, hands grasping desperately at nothing. “Oh, fuck, Pappy…” It turned him on to no extent knowing that his brother had become so lewd because of him.

“S-Shit…! S-Sans, nn…!” Paps, still a bit sensitive from last night, could feel that he was already getting close. “O-Oh, Sansy…!!”

“Are you alright, brother?” Sans panted worriedly, though he didn’t halt his grinding. An eager nod caused him to don an open-mouthed smile, a bright blue tongue hanging out. “Good, mweheh, because, ah… B-Because I want to do to you… What you did to me, last night,” An almost nervous chuckle, “I want to fuck you, Pappy.” Papyrus gasped and arched his spine at his brother’s words, his cum spilling onto his and Sans’ ribs.

“Nh, fu-fuck…! Nph…” Sans moaned at the sight of this, Papyrus’ magick warm on his bones. He licked his teeth as he stared down at the mess his brother had made.

“I wonder…” Releasing Paps’ wrists, he made his way down the taller skeleton’s body. A gentle lick to his lower-sternum had Papyrus clutching at the pillow beneath his head. “Tell me if I’m doing something wrong, Papyrus; I’ll stop if you want me to.” Sans said in all seriousness, though his eyes betrayed that he truly didn’t want to end this game.

“Don’t you… F-Fucking dare stop… Nph… I-In fact, oh fuck… B-Be as rough as y-you want, Sansy…” The last bit was a devious purr with a hint of desperation in it. Sans moaned again and found himself burying his teeth into one of his brother’s lower ribs. Papyrus gasped and clenched his teeth with a pleased growl. With a smirk, one full of lust and even greed, Sans let his tongue mold to the dips and grooves his teeth had left in the bone. Then he went on to clean away the orange mess on his brother’s ribcage. Papyrus was a mess of shuddering bones beneath him, moaning and growling with different strokes of the tongue. And as Sans bit down roughly on the base of his spine, Papyrus came again, some of it landing on Sans’ cheek and creating a new mess for the smaller skeleton.

“Wow, Pappy,” Sans murmured rather seductively, “You’ve “jizzed” several times, already, because of me… I must be making you feel _really_ good…” Papyrus moaned in response as his brother rubbed the side of his skull lovingly against his member with a pleased purr. “I wonder how many times I can get you to do that…” A soft whimper in reply, followed by a squirm. “Mwehehe, you’re already getting firm again, brother,” A gentle lick to the tip had Papyrus arching his spine, “How long have you wanted to do this with me? You’re _very_ eager…”

“Years!” The gasp made Sans blink in surprise as he gently stroked his brother’s shaft.

“You could have just asked me, brother; I would have been _more_ than happy to try this with you.” The taller sibling groaned, grip tightening on his pillow when his tip was licked again. “Mm, you taste like honey, Pappy…” The smaller skeleton murmured before taking the tip into his mouth and beginning to suck. Paps hissed in pleasure and clawed at his pillow, breathing quick through clenched teeth. “Mm…” Sans let his head sink down as far as he could before pulling it back up, turning his eyes to his brother’s pleasure-soaked expression. Papyrus was staring down at his desperately, obviously wanting to cum again. Sans gagged a bit as he dipped his head back down before squeezing his eyes shut in determined concentration and pushing himself further. His brows furrowed when Papyrus’ cock slipped back into his throat, and he had to draw off to breathe again, panting heavily. Opening his eyes, he looked back up at Paps, who was biting one of his phalanges when a sudden thought crossed his mind. “By the way, Papyrus, why did you start so early, last night?” It took him a few seconds to understand what Sans meant, but when he did, Papyrus blushed almost shamefully.

“Saw you… In nothing but a nightshirt… Was too good… Not to fantasize about…!” Sans raised a brow.

“And what did you fantasize?” He asked before going back to sucking slowly.

“A-Ah… Fu… Fucking you, s-sucking you off… Y-You sucking me o- A-Ah! Fuck, Sans, faster! O-Oh…!! Suck me harder, _please_!” The smaller sibling moaned and began to pick up the speed, tongue messily massaging the underside of the shaft and filling the room with soft slurping sounds. As he sped up, one hand stroking himself, Papyrus let go of his pillow and rest his hands on the back of Sans’ skull. Sans gripped his brother’s hips tightly, fingers scratching the edges of his pelvis as Papyrus began to push his head down in a sloppy rhythm. “Sans, oh, I’m gonna…! I’m about to…!!” Sans, knowing what he wanted and finding in the fuzz that was currently his mind that he somehow knew how to get it, pushed his mouth down to the base and swallowed as hard as he could. Papyrus let out a choked cry and came for a third time that morning, hips thrusting upward. Sans moaned as the liquid magick filled his mouth and slid down his throat, some of it running down from the corners of his mouth. He sat up, vision blurry, orange still lingering on his mouth and chin.

“Mwehehe… O-Oh?” His eyes focused and his expression turned to worry; while Papyrus wore a broad smile and his tongue had lolled out, there were bright orange tears trailing down his shed cheeks. “Pappy, you’re crying!! Are you okay?! Did I hurt you?!” Papyrus shook his head, still dazed.

“Felt… So good… Ah…” Was all he managed to get out. Sans stared at him in surprise, finding that a smirk was slowly forming on his face.

“Wait, so you’re actually crying because of the pleasure?” He cupped Paps’ cheek, and his brother leaned into his touch with a content sigh and a sheepish chuckle. His body was a blushing, trembling mess.

“Heheh, yeah…” The taller brother gulped when his sibling’s smirk grew.

Sans, leaning down so that his mouth was close to the side of his brother’s skull, whispered, “Then I’m going to make you _sob_ …” He pulled Paps’ hips up against his and ground against him with a moan, and Papyrus gasped and whimpered loudly, fighting the urge to toss his head back onto his pillow.

“Y-You’re gonna… Ah… Overstimulate me? Nph…”

“If that’s what it’s called, then yes.” Sans huffed, eyes unfocused as he rolled his hips repeatedly against Papyrus’. _I’m already almost there…!_ The taller skeleton thought and bucked his hips up against his brother’s. Sans whimpered and tugged at Papyrus’ hoodie, which had been bunched up against his upper ribs. “Taking this off.” Sans’ words were almost a desperate growl, and Paps nodded quickly in agreement. The smaller sibling looked over his brother with a dark blush once he was bare. “You’re so handsome, Pappy…” He breathed, leaning down to nibble his cervical. Papyrus’ breath hitched again and he squirmed, fingers tightly gripping Sans’ shoulders. “I wonder if you can do it again just from me biting you bones… Or, I could just make you watch me touch myself.” Paps shivered in delight at the thought.

“W-When did you get like this, bro?” He wheezed as Sans sat back.

“I don’t know, but I’m loving what it does to you, brother; you’re an absolute mess…” The taller sibling moaned shakily in response. “Nh, now watch me, Pappy…” Papyrus didn’t notice when his hands were pinned in place with magick above his head, all focus on the small hand that stroked its master’s shaft at a slow pace. “O-Oh… Mm, Papyrus, it feels so good… Ah… I’m touching myself because of you, Pappy… On top of you, too…” Sans moaned at his own words and began to buck into his hand at a faster rate, leaning back on one hand and bowing his head.

“O-Oh, fuck, bro… Seeing you like this is doing wonders for me… Not to mention my cock.” Sans smirked again, peering up at his brother.

“Mwehehe, how lewd, brother…”

“S-Says, ah, the one m-masturbating above me.” Sans brows furrowed as he picked up pace.

“P-Pappy, I’m so close…!” He whimpered, arching his spine inwards a bit.

“Fff… Bro, I need you to cum on me.” A soft groan in response had Papyrus squirming and struggling to get his hands free.

“Really?”

“ _Yes_ , I want you to cum all over me, fuck, I need to be _drenched_ in it! Nph, I’ll probably get off on just _that_!” To prove his point, he bucked his hips desperately again. Sans laughed a bit, then bit his tongue as he pumped himself and thrust into his hand at a quick pace.

“Oh, oh, oh, ah, fuck, Pappy, ah…!” His moans and whines were growing louder and higher in pitch with less space in between. “Hn, nn, _ah_! _Pap_!!” Sans rode out his orgasm through his hand as his cum coated his brother’s sternum, ribs, and spine. Papyrus whimpered and inhaled sharply, jerking his hips up and closing his eyes as he came as well. His magick dripped off Sans’ pelvis, coccyx, and lower spine.

“Fu…! Sa…! Nn…”

“O-Oh… We’re all sticky now, brother,” Papyrus inhaled shakily, “Feels good… Mwehehe, you’ve cum four times, now.”

“Ha… Sans… Bruh… Shi…” The taller skeleton’s eyes were unfocused and his body was limp.

“You can’t even form words… I’m going to make it five.” Papyrus whimpered, jerking up and crying out when teeth gently scraped his collarbone. “E-Eh? A-Are you okay, Pap? Is that a place I shouldn’t touch?” Sans asked nervously.

“No, ju…st so… sens…itive…” Papyrus managed out, leaning his neck back into Sans’ mouth.

“I see… Mweheh…” The smaller skeleton was rewarded with gasps and loud moans as his teeth and tongue worked over his sibling’s cervical.

“S…ans… T-Tou…ch me, plea…se…” Sans chuckled, letting his fingers wander over Papyrus’ ribs. He fingered the slot gently, feeling Paps arch his body up against his. “I’m… Ah… Gonna…” Sans suddenly stopped with yet another smirk, drawing out a disappointed whine from his brother.

“I want you to _beg_ for it, this time, Pappy…”

“Ah…! F-Fuck… P-Please…! Please, Sansy, let me cum! H-Help… Help me cum! _Please_!” The shorter sibling shivered and reached a hand down, and only seconds later it was sticky. Papyrus’ mind was reeling; he’d never felt this kind of pleasure, before, and he wouldn’t have ever imagined he would feel it because of his “innocent” brother. He hadn’t even realized he was talking until he heard something along the lines of “slut for you” come from his mouth. He had expected his brother to be surprised, or even angry by his vulgar statement. He _hadn_ ’ _t_ expected for Sans to look even more aroused than before… and for his eyes to be shaped like little blue hearts. Papyrus’ soul skipped nervously; if Sans was going into heat…

“You are, aren’t you, Pappy?” …Well, he didn’t really care. “My perfect brother, all splayed out for me… I’m going to fuck you, now.” Papyrus shivered and found himself already spreading his legs. “Needy, aren’t you?” The taller of the two nodded eagerly. “And what are you needs for? You needy for me?” Paps nodded again, hypnotized by his sibling’s predatory expression. Sans licked hungrily over a canine, eyes gleaming. “You needy for this cock? _My_ cock?”

“Yes, _yes_!!” Sans began to rub the tip of his member along the edges of Papyrus’ pelvis, already achingly hard.

“You said to be as rough as I want, right?”

“Mmhm!” With a grunt and a single hard thrust, Sans’ hip were pressed flush against his brother’s. “Ah- _Ha_!!” Papyrus choked out a cry, fingers nearly tearing the case of his pillow, head thrown back and body arched. Sans hesitated for the first time since he had bitten Papyrus’ collarbone.

“Nn… Y-You okay, brother?”

“Sa…! Ahn…! Ah…! Fuck…!” Since he couldn’t seem to form any solid thought, Paps settled for a feeble nod. Sans moaned, leaning into his brother and nuzzling the side of his skull.

“Feels so good… Gonna make _you_ feel so good, Pappy…” He rocked forward with another moan as his sibling’s fingers dug into his shoulder blades. Pulling halfway out, he thrust gently back in and started a slow rhythm. Papyrus tiredly clung to his brother with his arms and legs, Sans’ heat trying to fog his mind.

“S-Sans… Nnh, p-please…” And that seemed to snap the shorter skeleton back into his primal state as he began to piston his hips back and forth at an almost impossible rate, Papyrus crying out beneath him. He began to groan and grunt as he wrapped his arms under Paps’ spine and pulled him up as close as he could.

“Gonna, _nn_ , fuck you so, _mm_ , good, Pappy, that you can’t, _fuck_ , even speak…!! Gonna fuck you so good, _ah_ , gonna slam you so hard into the bed with my cock that you can’t even _think_ of anything other than my name! _Ah_ , ah, ah…!” Tears were streaming down the taller skeleton’s face again and he could do nothing, _wanted_ to do nothing but take what his brother gave him, reduced to a bundle of quivering bones and desperate nerves. He could feel Sans’ heat taking over _him_ , as well.

“S-Sans,” He whimpered, “Sansy, I’m gonna…!”

“ _Do it_ ,” Sans’ words came out a greedy growl, “ _Cum_ for me, brother…” That sent shivers to Papyrus’ very soul.

“Sansy, I…! _Sans, I_ ’ _m coming_!!” Sans growled and bit hard enough into his neck that the marks would last for quite a while, reaching his own climax with a loud grunt and clutching Papyrus close as he stilled. Paps went slack, having briefly blacked out, before resting his skull against his brother’s; it was all he could do. As Sans slowly pulled out, Papyrus vaguely noted that he loved the way his sibling’s member scratched against his tailbone just right.

“Mm… You alright, Pappy?” It took him a moment to muster a nod. “Mwehehe, good, because don’t think that we are done, yet.” And then Papyrus found that Sans was sitting on his chest and rubbing his still-dribbling cock on his chin. “Open up.” If anyone heard any strange sounds while passing their house, you could bet that a lizard-lady would hear about it.

**Notes for the Chapter:**

> NOW TO GET BACK TO SBL AHAHAHAHAHAHA


End file.
